Specifications

2.8.9 Example of Closed Loop PID Control
In a ventilation system, maintain the temperature at a
constant value. The desired temperature is set between -5
and +35 °C using a 0-10 V potentiometer. Because this is a
cooling application, if the temperature is above the set-
point value, increase the speed of the fan to provide more
cooling air flow. The temperature sensor has a range of -10
to +40 °C and uses a 2-wire transmitter to provide a 4-20
mA signal. The output frequency range of the frequency
converter is 10 to 50 Hz.
1. Start/Stop via the switch connected between
terminals 12 (+24 V) and 18.
2. Temperature reference via a potentiometer (-5–
+35 °C, 0–10 V) connected to the following
terminals:
•
50 (+10 V)
•
53 (input)
•
55 (common)
3.
Temperature feedback via transmitter (-10–40 °C,
4–20 mA) connected to terminal 54. Switch S202
behind the LCP set to ON (current input).
Temperature
Fan speed
Temperature
transmitter
Heat
Heat
generating
process
Cold air
130BA218.10
100kW
n °CW
Illustration 2.25 Closed Loop Control for a Ventilation System
Introduction VLT® HVAC Drive FC 102 Design Guide
36 MG16C102 - Rev. 2013-08-20
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